首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   530015篇
  免费   45597篇
  国内免费   19529篇
耳鼻咽喉   3764篇
儿科学   10249篇
妇产科学   6203篇
基础医学   86832篇
口腔科学   10048篇
临床医学   42974篇
内科学   85261篇
皮肤病学   7238篇
神经病学   37988篇
特种医学   11142篇
外国民族医学   132篇
外科学   39303篇
综合类   78017篇
现状与发展   68篇
一般理论   31篇
预防医学   29244篇
眼科学   8313篇
药学   67807篇
  77篇
中国医学   21770篇
肿瘤学   48680篇
  2024年   790篇
  2023年   7258篇
  2022年   10968篇
  2021年   22036篇
  2020年   17818篇
  2019年   17733篇
  2018年   17198篇
  2017年   17467篇
  2016年   17861篇
  2015年   20197篇
  2014年   30468篇
  2013年   34565篇
  2012年   30649篇
  2011年   35521篇
  2010年   29990篇
  2009年   29581篇
  2008年   28824篇
  2007年   28126篇
  2006年   25542篇
  2005年   23068篇
  2004年   19509篇
  2003年   17138篇
  2002年   13314篇
  2001年   11944篇
  2000年   9981篇
  1999年   9089篇
  1998年   7474篇
  1997年   6780篇
  1996年   6275篇
  1995年   5555篇
  1994年   5004篇
  1993年   4317篇
  1992年   3710篇
  1991年   3332篇
  1990年   2810篇
  1989年   2424篇
  1988年   2267篇
  1987年   1820篇
  1986年   1603篇
  1985年   2343篇
  1984年   2362篇
  1983年   1596篇
  1982年   1783篇
  1981年   1428篇
  1980年   1218篇
  1979年   986篇
  1978年   776篇
  1977年   624篇
  1976年   611篇
  1975年   415篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
《Clinical neurophysiology》2020,131(7):1444-1452
ObjectiveTo investigate cognitive functions in non-demented patients with early-onset Parkinson's disease (PD), and to compare PARK2 gene mutation carriers and non-carriers by means of event-related brain potentials (ERPs).MethodsThe participants comprised patients with early-onset PD (EOPD) and healthy controls (HC). Patients with EOPD were divided into two groups as carriers of known pathogenic variants of PARK2 gene (EOPD-PC) and non-carriers of genes involved in familial PD (EOPD-NC). ERP data were collected during auditory oddball and visual continuous performance test (CPT).ResultsBoth EOPD groups (EOPD-PC and EOPD-NC) displayed reduced and delayed P3 in response to oddball target and CPT NoGo. CPT Go P3 was reduced in EOPD-NC but not in EOPD-PC. Oddball target N1 was reduced and P2 was enhanced in both EOPD-PC and EOPD-NC. In both cognitive tasks, RTs were prolonged and accuracy was lower in EOPD-PC and EOPD-NC.ConclusionsWe found several EOPD-related neurophysiologic changes, implying impairments in cognitive functions. Pairwise comparisons between EOPD-PC and EOPD-NC revealed no significant ERP marker.SignificanceIn this study, the confounding effect of normative aging was somewhat excluded compared with many previous studies. In contrast with the many oddball studies in non-demented PD, we clearly observed reduced and prolonged P3 in early-onset PD. Our NoGo P3 findings also contribute to the limited ERP research concerning response inhibition.  相似文献   
105.

Background

Resistin is an immunometabolic mediator that is elevated in several inflammatory disorders. A ligand for Toll-like receptor 4, resistin modulates the recruitment and activation of myeloid cells, notably neutrophils. Neutrophils are major drivers of cystic fibrosis (CF) lung disease, in part due to the release of human neutrophil elastase- and myeloperoxidase-rich primary granules, leading to tissue damage. Here we assessed the relationship of resistin to CF lung disease.

Methods

Resistin levels were measured in plasma and sputum from three retrospective CF cohorts spanning a wide range of disease. We also assessed the ability of neutrophils to secrete resistin upon activation in vitro. Finally, we constructed a multivariate model assessing the relationship between resistin levels and lung function.

Results

Plasma resistin levels were only marginally higher in CF than in healthy control subjects. By contrast, sputum resistin levels were very high in CF, reaching 50–100 fold higher levels than in plasma. Among CF patients, higher plasma resistin levels were associated with allergic bronchopulmonary aspergillosis, and higher sputum resistin levels were associated with CF-related diabetes. Mechanistically, in vitro release of neutrophil primary granules was concomitant with resistin secretion. Overall, sputum resistin levels were negatively correlated with CF lung function, independently of other variables (age, sex, and genotype).

Conclusions

Our data establish relationships between resistin levels in the plasma and sputum of CF patients that correlate with disease status, and identify resistin as a novel mechanistic link between neutrophilic inflammation and lung disease in CF.  相似文献   
106.
107.
108.
目的:观察电针双侧"足三里"穴对脾气虚模型大鼠小肠黏膜上皮组织内的钠依赖葡萄糖转运体(SGLT1),葡萄糖运载蛋白2(GLUT2)的基因及蛋白表达的影响。方法:将40只SD雄性大鼠随机分为正常组、脾气虚组、足三里组、非经非穴组,每组10只。所有大鼠均在SPF级动物实验中心饲养。除正常组外,其余3组均采用劳倦过度和不规则饮食复合法建立脾气虚证的大鼠模型。造模成功之后,对足三里组、非经非穴组大鼠分别进行电针"足三里"穴、非经非穴点干预处理7天。采用HE染色方法观察各组大鼠小肠黏膜组织形态变化;采用荧光定量PCR法检测大鼠小肠黏膜上皮的SGLT1和GLUT2的mRNA表达水平;采用蛋白质免疫印迹法(WB)检测大鼠小肠黏膜上皮组织内的SGLT1和GLUT2的蛋白含量变化。结果:脾气虚组大鼠小肠黏膜组织部分损伤,足三里组的小肠黏膜组织有一定程度的恢复;脾气虚组和非经非穴组大鼠小肠黏膜组织内的SGLT1和GLUT2蛋白和基因表达水平均明显低于正常组(P 0. 05);足三里组大鼠小肠黏膜组织内的SGLT1和GLUT2蛋白和基因表达水平相比于脾气虚组有所升高(P 0. 05),非经非穴组未见显著性差异(P 0. 05)。结论:电针"足三里"穴可以调节脾气虚大鼠小肠黏膜上皮组织内的SGLT1和GLUT2基因及蛋白的异常表达,参与小肠对葡萄糖的吸收作用进而改善脾气虚证。  相似文献   
109.
110.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号